How is the myid value set for a ZooKeeper ensemble member?

How is the myid value set for a ZooKeeper ensemble member?

• A. In a file named myid in the dataDir containing a single integer
• B. In the config file as myid
• C. In an environment variable named MYID
• D. In a file named myid in the dataDir containing a single integer in human-readable ASCII text

Answer: (D)

ZooKeeper uses a dedicated myid file in the dataDir to know each member’s unique ID in the ensemble. The file must contain a single integer written in plain ASCII text. When a server starts, it reads this value and uses it to map to the corresponding server.x entry in the configuration (zoo.cfg). Because the ID ties directly to the configured server entries, having just the digits with no extra characters ensures ZooKeeper can reliably identify and participate in the ensemble. If the file is missing or contains anything other than that single number, startup or membership can fail, since the ID must exactly match the configured server ID.

ZooKeeper uses a dedicated myid file in the dataDir to know each member’s unique ID in the ensemble. The file must contain a single integer written in plain ASCII text. When a server starts, it reads this value and uses it to map to the corresponding server.x entry in the configuration (zoo.cfg). Because the ID ties directly to the configured server entries, having just the digits with no extra characters ensures ZooKeeper can reliably identify and participate in the ensemble. If the file is missing or contains anything other than that single number, startup or membership can fail, since the ID must exactly match the configured server ID.